The rated flux maintenance life of an LED is the elapsed operating time over which an LED light source maintains a given percentage of its initial light output. The flux maintenance of an LED light source is dependent upon many variables, including the operating temperature, drive current, and technology and materials used to construct the product. As such, the flux maintenance of LEDs can vary not only from manufacturer to manufacturer, but also between different LED package types produced by a single manufacturer. Further, it is important to consider the inherent limits to projected source life as extrapolated from test data. This document updates its recommended method of projecting the flux maintenance of LED light sources from the data obtained by IES LM-80 testing. The update of this document was accomplished by a dedicated TM-21 Working Group of LED industry professionals. The analyses of the IES LM-80 test data provided by major LED manufacturers are used to rationalize and support this document. Much of the IES LM-80 data came from testing that extended to 9,000 hours, and in some cases beyond.
